and mitt romney meet in their first presidential debate. watch and engage with c-span with our live debate preview at 7:00 p.m. eastern, followed by two ways to watch the debate at 9:00. on c-span, both candidates on- screen the entire debate. on c-span 2, multiple cameras. follow our live coverage on c- span, c-span radio, and online at c-span.org. >> coming up tonight on c-span, scholars examined whether presidential debates still matter. that is followed by a look at the role of social media. later, another chance to see the texas senate debate from tonight betwe. tomorrow on "washington journal. " abby kiesa is our guest. then were hear from robert erikson with a preview of tomorrow night's debate. later, an examination of the reasons why people vote. "washington journal" with this month, as the presidential cannot afford a great -- the debate, -- as the presidential candidates meet for a debate, we are asking students to submit to they are asking, what is the most important issue in the campaign, for the grand prize of $5,000. ca c-span cm competition is open to students grades6 throu